U.S. Pat. No. 3,539,794 (Rauhut, American Cyanamid, 1970) mentions a first sealed pouch containing a liquid included in a second sealed pouch and containing another liquid, with the means for breaking open the first pouch but without describing the means used.
The document EP-1421314 (Ladyjenski) describes a pouch of aluminum film containing an oxalate solution, disposed in the interior of a pouch of translucent plastic film also containing the enhancing solution. The device includes a steel ball or grain of hard matter whose role is to burst the aluminum pouch at the time of use, caused by the user's manipulation.
This device, however, presents certain drawbacks, of which is, in particular, the risk of unwanted piercing of the internal sachet during various manipulations, including during fabrication, filling, transport, and/or prolonged storage.
In addition, laminated, multilayer packaging films are very resistant, as a consequence of the materials chosen for their fabrication, particularly polyethylene, polypropylene, or PVC as a first layer, aluminum as a barrier film, and generally a layer of polyester film serving to protect the extremely thin aluminum barrier. The use of a ball or a grain of hard matter is not suited to breaking this type of film.
In addition, the use of a cutting object integral with the package does not appear to be adequate, either in view of the risk of undesirable rupture of the external pouch of the package or of the rupture of the internal pouch.